3350-30-9Relevant articles and documents
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Prelog et al.
, p. 471,479 (1953)
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Sethi,D.S. et al.
, p. 2632 - 2634 (1968)
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Synthesis of Cyclic Peptide Mimetics by the Successive Ring Expansion of Lactams
Stephens, Thomas C.,Lodi, Mahendar,Steer, Andrew M.,Lin, Yun,Gill, Matthew T.,Unsworth, William P.
, p. 13314 - 13318 (2017/10/05)
A successive ring-expansion protocol is reported that enables the controlled insertion of natural and non-natural amino acid fragments into lactams. Amino acids can be installed into macrocycles via an operationally simple and scalable iterative procedure, without the need for high dilution. This method is expected to be of broad utility, especially for the synthesis of medicinally important cyclic peptide mimetics.
Cascade rearrangement of spiroepoxymethyl radicals into 2-oxocycloalkyl radicals: Evaluation of a two-carbon cycloalkanone ring expansion
Afzal, Mohammad,Walton, John C.
, p. 937 - 945 (2007/10/03)
Series of 2-bromomethyl- and 2-hydroxymethyl-1-oxaspiro[2.n]alkanes were prepared from cycloalkanones by initial Wadsworth-Horner-Emmons methodology to afford ester-substituted methylenecycloalkanes. The latter were selectively reduced to hydroxymethylmethylenecycloalkanes which were epoxidised with peroxyacetic acid. Homolytic reactions were studied by EPR spectroscopy which enabled transient 3-oxoalk-1-enyl radicals, and their cyclisation products, 2-oxocycloalkyl and 2-oxocycloalkylmethyl radicals, to be characterised. This evidence, together with end product analyses of organotin hydride reductions of the 2-bromomethyl-1-oxaspiro[2.n]alkanes, established that the initial spiroepoxymethyl radicals rearranged by a three-stage cascade of two consecutive β-scissions followed by a cyclisation. Cyclisations of the 3-oxoalk-1-enyl radicals took place mainly in the endo-mode to afford 2-oxocycloalkyl radicals, except for the 5-oxohept-6-enyl radical for which exo-cyclisation to generate the 2-oxocyclohexylmethyl radical was preferred. Kinetic data for the exo-and endo-cyclisations of the 4-oxohex-5-enyl radical were obtained from tributyltin hydride mediated reactions of 2-bromomethyl-1-oxaspiro[2.3]hexane.
